Rotor blades of the abovementioned type are used in gas turbines to convert the energy of a hot gas flow into rotational energy. They typically have a blade airfoil, which is penetrated by cavities for carrying cooling air and which is fastened on a “platform”. Adjoining the platform there is a fastening region for fastening the turbine blade on the rotor or stator of the gas turbine.
Currently, rotor blades for gas turbines are produced by casting from a single piece and a single material. This is generally performed by way of the vacuum precision casting method. As part of further improvement in the efficiency of current gas turbines, particularly by increasing the mass flow, it has been found, however, that stability problems can occur with turbine blades produced by this method. Moreover, the mold used to produce the cooling ducts is generally not reusable.